ngrep strives to provide most of GNU grep's common features, applying them to the network layer. ngrep is a pcap-aware tool that will allow you to specify extended regular or hexadecimal expressions to match against data payloads of packets. It currently recognizes IPv4/6, TCP, UDP, ICMPv4/6, IGMP and Raw across Ethernet, PPP, SLIP, FDDI, Token Ring and null interfaces, and understands BPF filter logic in the same fashion as more common packet sniffing tools, such as tcpdump and snoop.

I compiled it from source and packaged it for maemo, that means it IS optified.

Know issues
It uses wmaster0 as default libpcap interface but our case the wlan0 interface is more interesting
This can be solved by using ngrep -d wlan0

I did not test this thoroughly but it seems to be working fine. That means, compiled without errors and it seemed to work when issuing ngrep -d wlan0